LibJS: Assign getter/setter function names as early as possible

In case of {get func() {}, set func() {}} we were wrongly setting the
function name to 'func' and then later trying to replace an empty name
with 'get func'/'set func' which failed.

Instead, set the name to 'get func'/'set func' right away.
The code in put_by_property_key is kept, for when that is called
by put_by_value.

Userland/Libraries/LibJS/Tests/object-basic.js

@@ -221,13 +221,13 @@ describe("naming of anon functions", () => {
         expect({ func() {} }.func.name).toBe("func");
     });
 
-    test.xfail("getter has name", () => {
+    test("getter has name", () => {
         expect(Object.getOwnPropertyDescriptor({ get func() {} }, "func").get.name).toBe(
             "get func"
         );
     });
 
-    test.xfail("setter has name", () => {
+    test("setter has name", () => {
         expect(Object.getOwnPropertyDescriptor({ set func(v) {} }, "func").set.name).toBe(
             "set func"
         );